Hydraulic pulsation absorption system



June 15, 1965 B. SPRAYBERRY ETAL 7 HYDRAULIC PULSA'I'ION ABSORPTION SYSTEM Filed March 25, 1963 2 Sheets-Sheet l IN VENTORS 1 BRYCE I SPRAYBERRY BY CHARLES W BROWN ATTORNEY 5 June 15, 1965 B. l. SPRAYBERRY ETAL 3,133,975

HYDRAULIC PULSATION ABSORPTION SYSTEM 2 Sheets-Sheet 2 Filed March 25, 1965 mY RR w mg a mm mm WW @m w .5 w m & aw QV v Y mm mw mm Qm G we N\ m C \J W H r mw Q Q wm mm United States Patent HYDRAULIQ PULSATION ABSORPTION SYSTEM Bryce I. Sprayberry, Atlanta, and Charies W. Brown,

Decatur, Gas, assignors to Southeastern Elevator Company, a Division of Turubull Elevator, Inc, Atlanta,

Ga., a corporation of Georgia Filed Mar. 25, 1963, Ser. No. 267,533 '13 Claims. (Cl. 103-224) This invention relates to a system for absorbing the pulsations and variations in pressure which generally characterize the flow of liquids, and more particularly to a system for absorbing and eliminating the objectionable pulsations, pressure variations and vibrations which a pump, such as a positive displacement pump, causes in a closed hydraulic system, such as a hydraulic elevator.

The flow of liquids in pipes resulting from the action of hydraulic pumps is generally characterized by some pulsations and variations in velocity and pressure because a steady uniform flow of liquids is extremely difiicult to achieve. It is practically impossible to achieve when the flow of the liquid is first initiated. The hydraulic systems used with hydraulically operated elevators are particularly subject to pulsations and variations in velocity and pressure. This is because the flow of liquid must be frequently started and stopped as the elevator is moved from one position to another, because the positive displacement pumps customarily used inherently cause pulsations and variations in the pressure and velocity of liquids, and because the closed system is of relatively short length.

This invention eliminates pulsations and variations in the pressure and velocity of a liquid even in the closed hydraulic system of a hydraulically operated elevator. Thus, it eliminates the objectionable pulsations and vibrations which have previously been associated with hydraulic elevators.

The invention achieves this improvement in closed hydraulic systems by creating an air cushion each time operating pressure is developed in the closed hydraulic system. This air cushion is created by an air pump whose operation is responsive to changes in hydraulic pressure in the hydraulic system. The liquid in the hydraulic system is exposed directly to the air cushion without interfering air bags, diaphragms or other material separation, as the liquid flows in the system through a bafiied mufiler containing both the air cushion and a low velocity liquid.

In this mufller, objectionable pulsations and pressure variations in the liquid are absorbed.

These and other features and advantages of the invention will be more clearly understood from the following detailed description and accompanying drawings, in which like characters designate corresponding parts in all figures, and in which:

FIG. 1 is a schematic presentation of a hydraulic system having the pulsation absorption device associated with it.

FIG. 2 is a section view of the muffler of the pulsation absorption device taken in a plane perpendicular to the centerline of the pipe section extending through the mufiier.

FIG. 3 is a section view of the mutlier of the pulsation absorption device taken in a vertical plane containing the centerline of the pipe section extending through the FIG 4 is a section view of the air pump of the pulsation absorption device taken in a vertical plane containing the centcrline of the air pump.

FIG. '5 is a schematic presentation of the hydraulic system for a hydraulically operated elevator and shows the pulsation absorption device as part of a hydraulic systern of this type.

These figures and the following detailed description 3,188,975 Patented June 15, 1965 disclose a preferred specific embodiment of the invention, but the invention is not limited to the details disclosed since it may be embodied in other equivalent forms.

The invention is best understood by considering the pulsation absorption system as comprisesd of an air pump 11 and a mufiier 12. The air pump 11 is a hollow cylindrical shell 13 open at both ends. its inside diameter at one end 14 and for a portion of its length extending from this end 14 is greater than its inside diameter at its other end 15 and for the rest of its length extending to end 15. The portion of the cylindrical shell 13 having the larger inside diameter is the hydraulic liquid chamber 16, and the portion of the cylindrical shell 13 having the smaller inside diameter is the air chamber 17. A circular shoulder 18 is formed within the cylindrical shell 13 where the hydraulic liquid chamber 16 joins the air chamber 17. The surface 19 of the shoulder 18 is perpendicular to the centerline of the cylindrical shell 13 and the width of the surface 19 is the difference between the inside diameter of the hydraulic liquid chamber 16 and the inside diameter of the air chamber 17.

An air piston 29 is slidably positioned within the air chamber 17. The outside diameter of the air piston SM) is substantially the same as the inside diameter of the air chamber 17, and the cylindrical surface of the air piston 21? has a sealing ring 21 or other sealing means embedded in it to prevent the passage of air around the air piston 20 as it slidably moves within the air chamber 17.

A liquid piston 22 is slidably positioned within the hydraulic liquid chamber 16. The outside diameter of the liquid piston 22 is substantially the same as the inside diameter of the hydraulic liquid chamber 16 and cylindrical surface of the liquid piston 22 has a sealing ring 23 or other sealing means embedded in it to prevent the passage of liquid around the liquid piston 22 as it slidably moves within the hydraulic liquid chamber 16.

A piston rod 24 joins the air piston 2'9 and liquid piston 22. The length of the piston rod 24 is selected so that when the liquid piston 22 is at the end 14 of the cylindrical shell 13, the air piston 2%) is at the shoulder 18 within the cylindrical shell 13. As the liquid piston 22 moves within the hydraulic liquid chamber 16 from end 14 toward the shoulder 18, the air piston 20 moves Within the air chamber 17 from the shoulder 18 toward the end 15 of the cylindrical shell 13.

The end 14 of the cylindrical shell 13 is closed by a liquid cap 25 which is attached to the end 14 by bolts 26. A seal such as an O-ring 27 is placed between the liquid cap 25 and the end 14 of the cylindrical shell 13, to prevent the escape of liquid. The end 15 of the cylindrical shell 13 is closed by an air cap 28 which is attached to the end 15 by bolts 2 An O-ring 27 or other sealing means is used between the air cap 28 and the end 15 of the cylindrical shell 13 to prevent the escape of air.

The liquid cap 25 has a liquid inlet hole 2? extending through it to provide access to the sealed hydraulic liquid chamber 16 and the air cap 28 has an air passage 30 extending through it to provide access to the sealed air chamber 17. A return spring 31 is positioned within the hydraulic liquid chamber 16 surrounding the piston rod 24- and with one end engaging the shoulder 18 and the other end engaging the liquid piston 22.

When liquid under pressure greater than the pressure exerted by the return spring 31 is introduced into the hydraulic liquid chamber 16 through liquid inlet hole 25 the liquid forces the liquid piston 22 toward the shoulder 18 and compresses the return spring 31. When the liquid pressure is reduced below that pressure necessary to com-- press the return spring 31, the return spring 31 expands and forces the liquid piston 22 toward the liquid cap 25 and the liquid out of the hydraulic liquid chamber 16 29 in the air'chamber 17 The'air passage'litl contains.

a check valve 32 of conventionalQtype which permits air to pass through the air passage30i from the air'chamber 17, but will not permit airto pass through the air passage 30 into the air chamber. .As a result, the motion of the air pistonr2l toward the, end 15 of the cylindricalshell 13 as the liquid piston 22 moves toward the. shoulder 18 under liquid pressure will cause air to be expelled under pressure from the air chamber 17 through the airpassage 30, but the motion of the air piston 24 toward the shoulder '18 as the liquid piston 22 moves toward the liquid cap 25 under return spring 31 pressure will not cause. air to enter the air chamber 17 through the passage 36.

Air enters the air chamber 17 only throughan air inlet channel 33. which extends within the wall of the air chamber. 17 and the air cap 28 from the hydraulic liquid chamber 16 to the air chamber 17. The. air inlet channel 33 has acheck valve '34 ofconventional type'positioned within it which permits air to pass through the air inlet channel 33 from the hydraulic liquid chamber .16 to the air chamber 1'7, but will not permit air to pass'through the air inlet channel 33 from the air chamber 17 to the hydraulic liquid chamber 16.

The air inlet channel 33 opens into the bottom 350f the hydraulicliquid chamber, 16at a point between the shoulder 18 andthe position of the liquid piston 22 when its motion toward the shoulder 13 is stopped by the air piston Ztl engaging the air cap 28. 'This location of the inlet opening 36 of the air inlet channel-33insures'that the liquid piston 22 will not close the inlet opening 36.

The location'also insures a constant supply of air for the air inlet channel 33 since thelspace in the cylindricalshe ll 13 between the liquid piston 22 and the air piston 20 is in direct communication with-the atmosphere through an air port 37. The air port 37 is also located in that length to the mochannel 33*andthe check valves 32 and 34 causes air to be expelled from the air chamber 17 through the air passage 36 asthe liquid piston 22, piston rod'24 and air piston "20. are forced toward the end of the cylindrical shell 13 byliquid pressure and to be drawn into the air chamber 17, through the air inlet channel 33 as the liquid piston 22, piston rod 24 and air piston are driven toward end 14 of the cylindrical shell 13 by return spring 31 pressure. Thus,.each time liquidlpressure is applied to the air pump 11, the air pump 11 expells a quantity of air under pressure through the air passage 30.

The air expelled from the air pump ll-through the air passage. is led by suitable tubing v38 of .known type to the mufller 12 ofthe pulsation absorption system. The mufller 12 is cylindrical in cross-section or of some other suitable shape and closed at both ends. A pipe section 39 extends thr'ough the mutfier 12.. Within the mufiler 12,

7 the pipesection 39 is positioned between the bottom 40 of 'mufiler 12 and the centerline of the mufller. 12 and with its centerline parallel to the centerline of the mufiier 12 in a vertical plane containing bothits centerline and the centerline of the mmi ler 12.1 p

A slot '41 passing completely through the wall of the pipe section39 extends the length of the pipe section 39 within the mutller '12.) This, slot 41 is in that portion of the pipe section ,39 neare'stthe bottom 40 of the muflier V 12 and is in the same vertical plane as the centerline of of the hydraulic liquid chamber 16 which is not traversed 7 by the liquid piston 22 as it moves toward and away from the shoulder 18.

The drawing of air into air port 37, a portion of the the air chamber 17 through the hydraulic liquid chamber 16 and the air inlet channel33 and the location of the inlet of the hydraulic liquid chamber 16 makes the'air pump 11 self cleaning and, if a lubri cating liquid is used, self-lubricating. In spite of the sealing ring 23, a small amount of liquid will pass around opening 36 in bottom'35.

the liquid piston 22 when liquid pressure is applied to the liquid piston 22 and-will pool in the bottom 35 of the hydraulic liquid chamberd16, If this pooled liquid is of a lubricating type, it will aid in lubricating the motion of the liquid piston 22in the hydraulic liquid chamber 161 'the mufiier. 12 and the 'centerline of thepipe section 39. Two, bafileplate s42are, positionedin the mufller 12 above thepipe section 39 and the centerline of the muffler. 12.. These baflie plates142 are in the same horizontal plane andextendthe length of the mufller12 from the opposite sides of the mufiier 12., The extending edges 43 of 7 i thebafiie plates 42 and'the ends of the mufiier 12 define a rectangular opening 44 between the portion of the muffler, 12 above the horizontal plane in which the baflie plates 42 lieand the rest of. the mother 12. The portion of the muffler 12 above the batlle plates 42 is the air cavity 45 and-the rest of the muffler 12 is the liquid cavity 46. The air fromrthe air pump 11 enters the mufiler 12 through an air inlet hole 47"which opens into the air cavity 45. V I

' In operation with a typical hydraulic system as shown in FIGURE 1, the pulsation absorptionsystem is assojciatedwitha closed hydraulic system by connecting the liquid inlet hole 29 of the air pump 11 to the hydraulic line 48 atia point between a hydraulic pump 49 driven by a, belt 5 3 and a hydraulic check valve-50 and by placing the pipe section 39 in the hydraulic line 48'as a section of the hydraulic line 48 at apointmore remote from the hydraulic pump 49 thanhthe check valve 50. The hydraulic pump 49, the checlryalve 5:0, and the-line 51 joining the. liquid inlet ,hole29 to the hydraulic line 48 are of lgnown type. i I

Initially, the closedhydraulic system is filled with liquid under zero hydraulic pressure when the hydraulic pump 49 'is not operating; With .zero hydraulic pressure However, when a vacuum is created in the air chamber 17 by the motion of air. piston 26 toward the shoulder 18,

the majority of this pooled liquid is drawn into the inlet opening 36 ahead of or with the air in the hydraulic liquid chamber 16. a

This drawing of the pooled excessive liquid from accumulating in the bottom 35 of the hydraulic liquid chamber 16. Within the air chamber 17, the liquid drawn into air chamber 17 will,if of'a lubriair pump 11 and the air lubricated.

' p The arrangementof the air passage 35 the air inlet liquid in the bolts-a 35 of a. I the hydraulic liquid chamber 16 into the inlet opening 36, the air inlet channel 33 and thexair chamber 17 prevents" on this portion of ahydraulic'system, the liquid piston 22 of the airpump' 11 is held adjacent to the liquid cap 25, the air chamber 17 isfilled'withair, and themufiler 12 7 contains liquidup to thelevel of the baffle plates '42.

Hydraulic'pressure is increased in the hydraulic system and movement of a ram such as that used withta hydraulic elevator is achieved by driving the hydraulic pump .49 with a belt 53iandladding additional liquid to the hydraulic system from a reservoir. 1 When operation of the hydraulic pump 49 is initiated, the hydraulic pressure first. begins-to develop in thehydraulic line between the cating'type, serve to lubricate the motion of the air piston 20 in the air chamber 17 and is expelled from the air pump 11 with air each time the air piston Ztlis forced toward ,the air cap 28. Thus, liquid will not accumulate in the pumpv 11 can be'continuously V hydraulic pump549. and the check valve 50. 'As the hydraulic pressure increases, the additional liquidbegins tc pass through the check valve SO andintothe hydraulic line' 48 beyond the checkyalve "50;" The result of thi:

initialflow of, liquid through thecheck valve 50 is to in 1 crease the hydraulic pressure on the liquid in the pipe sec ,tion' 39 andcause additional liquid to pass through the will again operate.

slot 41 into the mutller 12 and raise the level of the liquid in the muffler-12.

However, the increasing hydraulic pressure is being applied to the liquid piston 22 through the line 51 and as the hydraulic pressure increases, it reaches a pressure sufiicient to collapse return spring 31 and operate the air pump 11. This forces air into the air cavity 45 of the mutller 12 and places air in the rnufiier 12 above the liquid. The liquid will continue to rise in the muffler 12 and compress the air until the air pressure equals the hydraulic pressure. When the desired static or operating hydraulic pressure is established throughout the system, the air in the muffler 12 will be trapped in the mutiler 12 and will be exerting a pressure on the liquid equal to the hydraulic pressure. If the hydraulic pressure between the check valve 50 and the pump 49 is subsequently reduced to Zero, the return spring 31 will force the liquid piston 22 toward the liquid cap 25 and drive the liquid from the air pump 11. With the next application of hydraulic pressure to the hydraulic system, the air pump 11 Excess air does not accumulate in the mufiier 12 because of repeated operation of the air pump 11 since the flow of liquid through the mufiler 12 each time hydraulic pressure is developed between the pump 49 and the check valve 50 absorbs the excess air.

The quantity of air injected by the air pump 11 into the air cavity 45 each time the air pump 11 operates is fixed by the size of the air chamber 17 and the amount of air absorbed by the liquid becomes relatively constant after the hydraulic system has been operated several times. Thus, after several operations of the hydraulic system, the injected air and unabsorbed air trapped in the mutller 12 with each application of hydraulic pressure to the hydraulic system become relatively constant in quantity. For a fixed operating hydraulic pressure, this quantity of air will occupy the same space in the muffler lleach time the operating hydraulic pressure is applied to the hydraulic system.

The bafile plates 42 are positioned within the muffier 12 so that the space above them is substantially equal to space occupied by the injected air and unabsorbed air when the liquid in rnufller 12 is under operating hydraulic pressure. Thus, when the hydraulic system is under operating pressure, the liquid cavity 46 of the mutlier 12 is filled with liquid and the air cavity 45 is filled with air.

The air and the liquid in the mufiler 12 are in contact through the rectangular opening 44.

The air trapped in the air cavity 45 has greater compressibility than the liquid in the hydraulic system, and its resiliency in combination with the low velocity liquid in the liquid cavity 46 results in a pulsation absorption system which effectively absorbs pulsations and pressure variationsin the hydraulic liquid as it passes through the pipe section 39. The pulsation absorption system has proved particularly ettective in connection with hydraulically operated elevator systems such as that schematically shown in FIG. 5.

The elevator system is operated by oil pressure and has a motor 52, an oil pump 49 driven by a belt 53, a

control valve 54, an oil check valve a leveling valve 55, a lowering valve 56 and controls of conventional known type and arranged in the usual manner. The pump49 draws oil from a reservoir through its suction intake 57 and the hydraulic line 48 leads to the ram by which the elevator car is moved. The air pump 11 is connected to the control valve 54 and the mufller 12 is positioned in the hydraulic line 48. The elevator is op erated in the usual manner and the closing of the control valve 54 applies hydraulic pressure to the air pump 11 at the same time it applies hydraulic pressure to the hydraulic line 48 and starts upward elevator motion. The resulting air cushion in the mufiler 12 absorbs pulsations and pressure variations and prevents undesirable vibration of the elevator car as it moves upward.

When the elevator car stops after it has moved upward, the elevator car is maintained in position by the closed oil check valve 50 and closed lowering valve 56. The motor 52 is stopped and the hydraulic pressure on the oil pump 49 side of the oil check valve 50 drops to zero. This permits the air pump 11 to return to position for pumping additional air into the mufiler 12. The elevator car is lowered by opening the lowering valve 56 and releasing oil through it into the reservoir through pipe 58. The released oil carries absorbed air with it to the reservoir and the mufiler 12 is now ready to receive an additional quantity of air with the next application of hydraulic pressure from the pump 49.

If the elevator car moves upward several times before being lowered, the air pump 11 will operate each time the elevator car move-s upward from one floor to another. However, this does not result in an excessive amount of air in the air cavity 45 of the mutfier 12 since the additional oil passes through the pipe section 39 with each additional floor travelled by the elevator car absorbs most of the excess air as the elevator moves upward and carries it back to the reservoir when the elevator car is completely lowered. Moreover, the fact that the oil in the mutller 1.2 is always under the pressure exerted by the weight of the elevator car and ram and that the unabsorbed air in the mutiler 12 is always under some hydraulic pressure does not alter the general operation of the pulsation absorption device 11 described above. The air pump 11 operates with the hydraulic pressure of the hydraulic system and will force air into the air cavity 45 of the mutlier 12 even if oil in the mufiler 12 is under hydraulic pressure.

It will be obvious to those skilled in the art that many variations may be made in the embodiments here chosen for the purpose of illustrating the present invention with out departing from the scope thereof as defined by the appended claims.

What is claimed as invention is:

1. A pulsation absorption system for absorbing pulsations of hydraulic pressure in a hydraulic line with a particular hydraulic pressure, said pulsation absorption device comprising, in combination, a closed cylindrical shell having two ends, a bottom, a centerline, and a top through which an air inlet hole passes; a pipe section extending through the cylindrical shell between the centerline of the cylindrical shell and the bottom of the cylindrical shell, said pipe section having its centerline parallel to and in the same vertical plane as the centerline of the cylindrical shell, having its ends extending outside the cylindrical shell and inserted into the hydraulic line, and having a slot extending through that portion of its length within the cylindrical shell and along that side nearest the bottom of the cylindrical shell; two bailie plates positioned within the cylindrical shell above the centerline of the cylindrical shell, the said two baflle plates extending from opposite sides of the cylindrical shell, lying in the same horizontal plane, and defining with the two ends of the cylindrical shell a rectangular opening and with the two ends and the top of the cylindrical shell a volume; and means responsive to the particular hydraulic pressure in the hydraulic line for injecting through the air inlet hole that volume of air necessary to fill the volume defined by the two baffle plates and the two ends and the top of the cylindrical she-ll each time the particular hydraulic pressure is developed within the hydraulic line.

2. A mufller for absorbing pulsations of hydraulic pressure in a hydraulic line with an air cushion, said muffler comprising, in combination, a closed cylindrical shell having two ends, a bottom, a centerline, and a top through which an air inlet hole passes; a pipe section extending through the cylindrical shell between the centerline of the cylindrical shell and the bottom of the cylindrical shell, said pipe section having its centerline parallel to and in the same vertical plane as the centerline of the cylindrical shell, having its ends extending outside the section into the. hydraulic line, and having a I I ans 7 I rectangular opening and with the two ends and the top of y thecylindrical shell a volume; and means for injecting a quantity of air through the air inlet hole substantially equal to the volume defined by the two bafile plates and the two ends and the top of the, cylindrical shell;

r 3. A mufiler for. absorbing pulsations of hydraulic pressure in a hydraulic line with an air cushion of a closed cylindrical'shell having two' ends, a bottom, a

centerline, and a top; a pipersectionextending through the cylindrical'shell'between the'c'enterline of thecylindrical shell and-the bottornv'of the cylindrical shell, said pipe section having its centerline parallelto and in the ,same'vertical plane as the centerline of thefcylindrical shell, having its tends extending outside the cylindrical,

shelland adapted 'for insertion of the pipe section "into the hydraulic line, and having a slot extending through that portion of-its length within the cylindrical shell and along that sidetne arest the bottom of the cylindrical shell;

and two baflle plates positioned withinthe cylindrical shell above the centerline of the cylindrical shell, the said two bafile plates extending from opposite sides of the cylindrical shell, lying in the same horizontal plane, and defining with the two ends of the cylindrical shell a rec-- tangular opening and with the two ends and the top of the cylindrical shell a volume equal to the fixed volume t of the air cushion. a 4. A muffler for absorbing'pulsations of hydraulic pressure in a hydraulicilinewith a volume of air, said mufiler comprising, in combination, a shell having two ends and a top; a section of the hydraulic line extending through the shell and having a slot extending through a, portion of its length within the shell; means for introducing the volume of air into the shell; and two baffle plates positioned within the shell and enclosing with the two ends and the top of the shell the volume of air.

5. A muffler for absorbing pulsations of hydraulic pres sure in a hydraulic line with air, said rnufiier compris ing, in combination, a cylindrical shell having two ends.

.and a top through whichan air inlet hole passes; a pipe section extending thrcugh'the cylindrical shell, said pipe" sectionhaving its, ends extending outside the, cylindrical shell and adapted for insertion of, the pipesection' into vthe hydraulic line and having a slot extending'through a portion of its length within the cylindrical shell; two

,bafile plates positioned within thecylindrical shell, the said two bafileplates extending from opposite sides of the cylindrical shell and defining with the two ends and V t the top of the cylindrical shell a volume; and means for injecting air through the air inlet hole into the volume defined by the two bafile plates and the two ends and the top of the cylindrical shell. 1 e

6. A self-lubricating pump for ejecting a fixed quantity of air in response to the hydraulic 'pressureof a liquid in a hydraulic line greater than a particular hydraulic pressure comprising, in combination,a'cylindri'cal horizontally.

extending shell having a first end,Ta secondrend, a center-,: 6 line extending between the'first'end and the second end,

a cylindrical liquid chamberfextending into the cylindrical shell from the first end of the'cyl'indrical shell with its centerline' coinciding with' the centerline of the cylin I drical shell, an airport extending through the cylindrical shell into that portion of the liquid chamber most remote from the first end of the cylindrical'shell, 'avcylind rical air'chamber extending through the cylindrical shell-between the second end of the cylindrical shell and the" liquid chamber with its'centerline coinciding with the slot extend 515 fixed volume, saidrnmfifier comprising, n combination, a;

cnte'rline of the liquid ch'amber'andthe centerline' of the. cylindrical shell, said liquid chamber and said air chamber having different "diameters so as'to form a shoulder within the cylindrical shell gwhere'ithe air chamber :5 gjoins the liquid chamber; an .air channel-defined by said shell and extending between'the lower-most portion of theliq'uid; chamber adjacent'said'shoulder and the air chamber; a liquid piston slidably positioned within the liquid chamber; an-air piston slidably positioned within the airlchamber; a piston rod extending within the cylindrical shell "between' the liquid piston and the air piston with its centerline coinciding with the centerline of the cylindrical shell; a spring positioned, around the piston rod and extending'between the liquid piston and the shoulderwithin the'cylindrical shell, saidspring exerting pressure on the liquidtpiston equal to the particular hydraulic pressure; a liquid cap fixedly attached; to the first {end of the cylindrical shell across'the liquidichamber, said liquid cap having a liquid inlet hole extendin g'through it and into the liquid chamber; an ah cap fixedly attached to thejsecond end ofthe cylindrical shell across the air ,fchambe'r', said air can having an'air passage extending I through it and into .the air chamber; a first-check valve located within the air channel and positioned topermit the passage of air fonly from theliquid chamber to the 'air chamber; a second check valve located within the air passage and positioned to permit the passage of air only from theair chamber; and means for placing the liquid inlet hole in communication with the liquid in the hydraulic'line. l 7 s r "7. A self-lubricatin'gpump "for ejecting a fixed quantity of air-in response to the particular hydraulic pressure oi -a ,liquid'in a hydraulic-line comprising, in combination :ahorizontal. cylindrical shell having'a first end, a second end, a-"cylind'rical liquid chamber extending into the cylindrical shell fromthe first end of the cylindrical shell, as air port extending throughthe cylindrical shell into that portion of the liquid chamber most remote from the first 'endoftthe cylindrical shell, an air chamber extending 40 throughthe'cylindrical shell between the second ,end 01 the cylindrical shell and the liquid chamber and having at air channel extending between itand the lowermost por tion of; the liquid chambermost remote said first enc' through the cylindrical shell; 2. liquid piston slidably positioned-within the liquid chamber; an air piston slid gjably positioned within the air chamber; a piston rod ex tending'betwe'en theliquid piston'and the air piston; 2 spring positioned around the .piston rod and exerting pressure on the liquid piston equal to the particular hy draulic pressure; aliquid cap fixedly attached to the firs end of, the cylindrical shell across the liquid chamber said liquid. cap'having a liquid inlethole extending througl it into the liquid chamber; an air cap fixedly attached tr the second end of the cylindrical shell across the ai Echamber, said 'aircapha'ying" an air passage extendin; through it into the air chamber; a first checkvvalve lo cated within the air channel and positioned to permi Jthetpassa ge'of air 'only'from the liquid chamber to th lair Qchamberya second check'valve located within th air passage andpositioned to'permit the passage of ai only from the; air chamber; and means for placing th liquidinlet hole in communication with the liquid in th hydraulic line. Y t Y e 8. A self-lubricating pump :for' ejecting a fixed quar tity of air in responseto the'particular hydraulic pressur of a liquidiin a hydraulic line comprising, in combine tion, a horizontally positioned cylindrical shell having cylindricalliquid chamber with an air port and'a liqui inlet hole extending into it through the cylindrical shel 7 a cylindrical air .chamberwith an air passage extendin fiIliOi it through the cylindrical shell, and an air channe extending between the bottom portion of the liqui chamber adjacent said air chamber-and the air chamber; first pistonpositioned in the liquid chamber for slidabl 7'5 rn'otion withreference to the liquid inlet hole; a secon piston positioned in the air chamber for slidable motion with reference to the air passage; a piston rod extending between the first piston and the second piston; a spring engaging the'first piston and urging the first piston toward the liquid inlet hole with a force equal to the particular hydraulic pressure; a first check valve located within theair channel and positioned to permit the passage of air only from the liquid chamber to the air chamber; a second check valve located within the air passage and positioned to permit the passage of air only from the air chamber; and means for placing the liquid inlet hole I in communication with the liquid in the hydraulic line.

9. A self-lubricating pump for ejecting a fixed quantity of air in response to a particular hydraulic pressure of a liquid in a hydraulic line comprising, in combination, a closed horizontally positioned cylindrical shell having a hollow cylindrical chamber within it, a liquid inlet hole passing through its first end into the cylindrical chamber, an air passage passing through its second end into the cylindrical chamber, and an air port passing through it intermediate its first end and second end and into the cylindrical chamber; a first piston positioned within the cylindrical chamber for slidable motion toward and away from the first end of the cylindrical shell; a second piston positioned within the cylindrical chamber for slidable motion toward and away from the second end of the cylindrical shell; a piston rod extending between the first piston and the second piston; a spring positioned within the cylindrical chamber and having one end fixed and the other end engaging the first piston and urging the first piston toward the first end of the cylindrical shell with a pressure equal to the particular hydraulic pressure; and means for introducing liquid pooled between said first piston and said second piston into said air chamber for lubrication.

10. A self-lubricating pump for ejecting a fixed quantity of air in response to particular hydraulic pressure of a liquid in a hydraulic line comprising, in combination, a closed shell having a hollow chamber within it, a liquid inlet hole passing through its first end into the chamber, an air passage passing through its second end into the chamber; a first piston positioned Within the chamber for slidable motion toward and away from the first end of the shell; a second piston positioned within the chamber for slidable motion toward and away from the second end of the shell; a piston rod extending between the first piston and the second piston; means for urging the first piston toward the first end of the shell with a pressure equal to the particular hydraulic pressure; and means for introducing liquid pooled in said chamber between said first and second pistons into said chamber adjacent said second end.

11. A pulsation absorption system for absorbing pulsations of hydraulic pressure in a hydraulic line having a particular hydraulic pressure, said pulsation absorption system comprising, in combination, a cylindrical shell having two ends, a bottom, a centerline, and a top through which an air inlet hole passes; a pipe section extending through the cylindrical shell between the centerline of the cylindrical shell, said pipe section having its center line parallel to and in the same vertical plane as the centerline of the cylindrical shell, having its ends extending outside the cylindrical shell and inserted into the hydraulic line, and having a slot extending through that portion of its length within the cylindrical shell and along that side nearest the bottom of the cylindrical shell; two battle plates positioned within the cylindrical shell above the centerline of the cylindrical shell, said two bafiie plates ex tending from opposite sides of the cylindrical shell, lying in the same horizontal plane, and defining with the two ends of the cylindrical shell a rectangular opening and with the two ends and the top of the cylindrical shell a first volume; a tube having a hollow chamber within it, a first end, a second end, a liquid inlet hole passing through its first end from the hollow chamber, and an air passage passing through its second end from the hollow chamber; a first piston positioned within the said hollow chamber for slidable motion toward and away from the said first end of the tube; a second piston positioned within the hollow chamber for slidable motion toward and away from the said second end of the tube, said second piston defining when most remote from the second end of the said tube a cavity within the hollow chamber which has a volume substantially equal to the said first volume; means for causing air to enter the said cavity; a piston rod fixedly extending between the first piston and the second piston; means for urging the first piston toward the first end of the tube with a pressure slightly less than the particular hydraulic pressure; means for operatively connecting the liquid inlet hole with the hydraulic line; and means for operatively connecting the air passage to the said inlet hole.

12. A pulsation absorption system for absorbing pulsations of hydraulic pressure in a hydraulic line containing a liquid at a particular pressure, said pulsation absorption system comprising, in combination, a cylindrical shell having two ends and a top through which an air inlet hole passes; a pipe section extending through the cylindrical shell, said pipe section being inserted into the hydraulic line and having a slot extending in that portion of its length within the cylindrical shell through which the said liquid enters the cylindrical shell; two baflle plates positioned within the cylindrical shell above the pipe section, said bafile plates defining with the two ends of the cylindrical shell an opening and with the two ends and the top of the cylindrical shell a first volume; a gas substantially filling the said first volume; a tube having a hollow chamber'within it, a liquid inlet hole extending from the hollow chamber, and an air passage extending from the hollow chamber; a first piston positioned within the said hollow chamber for slidable motion toward and away from the liquid inlet hole; a second piston positioned within the hollow chamber for slidable motion toward and away from the air passage, said second piston defining when most remote from the air passage a cavity within the hollow chamber which has a volume equal to the volume of the gas in the said first volume absorbed by the liquid in the cylindrical shell; means for releasing a gas into the said cavity; a piston rod extending between the first piston and the second piston; means for urging the first piston toward the liquid inlet hole with a pressure slightly less than the particular hydraulic pressure; means for operatively connecting the liquid inlet hole with the hydraulic line; and means for operatively connecting the air passage to the air inlet hole.

13. A pulsation absorption system for absorbing pulsations of hydraulic pressure in a hydraulic line containing a liquid at a particular hydraulic pressure, said pulsation absorption system comprising, in combination, a cylindrical shell having an air inlet hole extending through it; a pipe section in the cylindrical shell, said pipe section being in the hydraulic line and having a slot extending through it to permit the said liquid to enter the cylindrical shell; bafile plates positioned within the cylindrical shell to define an opening and a first volpme; a gas substantially filling the said first volume and engaging the liquid in the cylindrical shell through the said opening; a tube having a hollow chamber within it, a liquid inlet hole extending from the hollow chamber, and an air passage extending from the hollow chamber; a first piston positioned Within the said hollow chamber for slidable motion toward and away from the liquid inlet hole; a second piston positioned within the hollow chamber for slidable motion toward and away from the air passage, said second piston defining when most remote from the air passage a cavity within the hollow chamber which has a volume substantially equal to the volume of the said gas absorbed by the liquid in the cylindrical shell; means :for releasingla "Refexences Cited by'the Examiner gas into the'said cavity; a piston rod exteriding b'etween UNITED STATES PATENTS the first piston afid fhe se cdrid pis tonj means for urging 7 2 04 /55 I the fi p to w d h l qu d inl tr h l with a pressure 2,735,504 2/56 'Moyer v slightly l ss than thevp artiqlila'r, hydraulic pressure; means 1 2,313,131 12/57, Doughty 181 36 for .opei ativelyconnectir g the liquid inlet hols with the 2,909,315 10/59 Sampietro 230-52 hydraulic line; and meanslfor operatively Om ecting the LAURENCE V EFNER, Primary Exa iner, I air passaget-o thejairinlet'holev i V W ALKER" Exdminen Y 

1. A PULSATION ABSORPTION SYSTEM FOR ABSORBING PULSATIONS OF HYDRAULIC PRESSURE IN A HYDRAULIC LINE WITH A PARTICULAR HYDRAULIC PRESSURE, SAID PULSATION ABSORPTION DEVICE COMPRISING, IN COMBINATION, A CLOSED CYLINDRICAL SHELL HAVING TWO ENDS, A BOTTOM, A CENTERLINE, AND A TOP THROUGH WHICH AN AIR INLET HOLE PASSES; A PIPE SECTION EXTENDING THROUGH THE CYLINDRICAL SHELL BETWEEN THE CENTERLINE OF THE CYLINDRICAL SHELL AND THE BOTTOM OF THE CYLINDRICAL SHELL, SAID PIPE SECTION HAVING ITS CENTERLINE PARALLEL TO AND IN THE SAME VERTICAL PLANE AS THE CENTERLINE OF THE CYLINDRICAL SHELL, HAVING ITS ENDS EXTENDING OUTSIDE OF THE CYLINDRICAL SHELL AND INSERTED INTO THE HYDRAULIC LINE, AND HAVING A SLOT EXTENDING THROUGH THAT PORTION OF ITS LENGTH WITHIN THE CYLINDRICAL SHELL AND ALONG THAT SIDE NEAREST THE BOTTOM OF THE CYLINDRICAL SHELL; TWO BAFFLE PLATES POSITIONED WITHIN THE CYLINDRICAL SHELL ABOVE THE CENTERLINE OF THE CYLINDRICAL SHELL, THE SAID TWO BAFFLE PLATES EXTENDING FROM OPPOSITE SIDES OF THE CYLINDRICAL SHELL, LYING IN THE SAME HORIZONTAL PLANE, AND DEFINING WITH THE TWO ENDS OF THE CYLINDRICAL SHELL A RECTANTULAR OPENING AND WITH THE TWO ENDS AND THE TOP OF THE CYLINDRICAL SHELL A VOLUME; AND MEANS RESPONSIVE TO THE PARTICULAR HYDRAULIC PRESSURE IN THE HYDRAULIC LINE FOR INJECTING THROUGH THE AIR INLET HOLE THAT VOLUME OF AIR NECESSARY TO FILL THE VOLUME DEFINED BY THE TWO BAFFLE PLATES AND THE TWO ENDS AND THE TOP OF THE CYLINDRICAL SHELL EACH TIME THE PARTICULAR HYDRAULIC PRESSURE IS DEVELOPED WITHIN THE HYDRAULIC LINE. 